Disclaimer

  • References: Nigeria Centre for Disease control (NCDC), see here:

Nigeria Center for Disease Control and Prevention

Nigeria Center for Disease Control and Prevention
  • More information: for a dynamic report of the 🇳🇬 Lassa fever situation in Nigeria , go to 🔗

Lassa fever in Nigeria - data from 2020 to 2024

The overall burden of Lassa fever in Nigeria

  • Nigeria has the highest burden of Lassa fever cases in West Africa.
  • Strengthening of capacity for laboratory diagnostics and case management in previous years resulted in greater case detection.
  • Major LF outbreaks reported in since 2018, with 5344 confirmed cases since 2020.

The effect of seasonality on the Lassa fever incidence

  • Lassa fever cases in Nigeria by week show a seasonal effect: the number of cases peaks during the dry season period (from epi week 47 - week 12).
  • The seasonal increase of Lassa fever cases during the dry period may be attributed to an increase of the infected rodent population, or a seasonal behavioural change in the human population (or a mix of both) resulting in a higher risk of exposure with infected animals and/or to food or household items contaminated with rodent excreta.

Lassa fever in Nigeria: where do efforts need to focus?

Cumulatively, from January 2018 to December 2024, 75% of all Lassa fever confirmed cases were from Ondo (33%), Edo (31%) and Bauchi (11%) States.

  • Total suspected cases: 38,518
  • Total confirmed cases: 5,850
  • Deaths from Confirmed Cases: 1,071
  • Case Fatality Ratio: 20%
  • Number of Health Care Workers: 228

Lassa fever suspected cases, confirmed cases and CFR by State, Nigeria 2020-2024

Lassa fever by State, Nigeria 2020-2024: Interactive maps

Suspected cases of Lassa fever

  • From 2017-2024, a total of 36,022 suspected cases were reported from 26 in Zamfara to 13,950 in Edo.

Case fatality rate (CFR) among confirmed Lassa fever cases

  • From 2017-2024, CFR among all laboratory confirmed cases in Nigeria was between 16-27% and decreased over the years.
  • In 2024, overall CFR for Nigeria was 16% and differed greatly by individual State.
  • In general, variation of CFR is likely due to late presentation of patients and differences in case management which may indicate a need for improvement.

Lassa fever infections among healthcare workers

  • From 2020-2024, a total of 212 healthcare workers (HCW) were reported among confirmed cases, that is 4% of Lassa fever cases.
  • From 2020-2024, 60% of all HCW infections were from Ondo (26%), Bauchi (20%), Edo (15%) States where 75% of all Lassa fever patients were being cared for. 12% of HCW infections are reported from Ebonyi where 6% of Lassa fever patients were being cared for.
  • Higher proportion of HCW in States with low incidence (10-30%).

Lassa fever in 2025 - Data from epi-week 1 to epi-week 8

Suspected cases of Lassa fever in 2025

  • In 2025, a total of 2,496 suspected cases were reported from 1 in Niger, Akwa Ibom to 797 in Edo.

Cumulative number of confirmed Lassa fever cases in 2025

  • Nigeria has the highest burden of Lassa fever cases in West Africa.
  • Strengthening of capacity for laboratory diagnostics and case management in previous years resulted in greater case detection.
  • Major LF outbreaks reported in since 2018, with 5344 confirmed cases since 2020.

Seasonality of Lassa fever

  • In 2025, similar trend as per previous years confirming a seasonal effect on Lassa fever incidence.
  • Compared to 2024, 12% decrease in the cumulative number of confirmed cases reported.

States reporting Lassa fever confirmed cases in 2025

  • In 2025, as of epi week 8, 89% of LF cases are from Ondo (32%), Bauchi (24%), Edo (17%), and Taraba (16%) States.

  • Total confirmed cases: 506

  • Deaths from Confirmed Cases: 95

  • Case Fatality Ratio: 19%

  • Number of Health Care Workers: 16

Lassa fever suspected cases, confirmed cases and CFR by State in 2025

Lassa fever by State, Nigeria 2025: Interactive maps

Case fatality ratio among confirmed Lassa fever cases by State in 2025

  • As of epi week 8 2025, cumulatively 506 cases and 95 deaths (CFR=19%) across 12 States have been reported
  • At same period 2024, a total of 24 States reported at least one confirmed cases.
  • There is a 22% decrease in the number of suspected cases reported in 2025 compared to 2024.
  • In 2024, 32 States had reported at least one suspected case versus 29 in 2025 to date.

Health care worker infections 2020-2025 epiweek 8

  • As of epi week 8 of 2025, there has been 16 healthcare workers infected, that is 3% of confirmed cases.
  • 8 HCW infections in Ondo, 4 in Bauchi, 2 in Gombe, 1 in Edo and 1 in Taraba.

Lassa fever in most affected States - Data from 2020 to 2025 (as of epi-week 8)

Lassa fever in Ondo State, 2020-2025





  • As of week 8, 2025, Ondo State reported 1939 confirmed cases including 282 deaths (CFR 15%).
  • In 2025 only, Ondo State reported 160 confirmed cases including 21 deaths (CFR 13%).
  • Compared to same period 2024, this represents a 24% increase in the number of confirmed cases and a 69% increase in CFR.

Lassa fever in Bauchi State, 2020-2025





  • As of week 8, 2025, Bauchi State reported 805 confirmed cases including 157 deaths (CFR 20%).
  • In 2025 only, Bauchi State reported 122 confirmed cases including 10 deaths (CFR 8%).
  • Compared to same period 2024, this represents a 42% increase in the number of confirmed cases and a 65% decrease in CFR.

Lassa fever in Edo State, 2020-2025





  • As of week 8, 2025, Edo State reported 1596 confirmed cases including 178 deaths (CFR 11%).
  • In 2025 only, Edo State reported 88 confirmed cases including 14 deaths (CFR 16%).
  • Compared to same period 2024, this represents a 41% decrease in the number of confirmed cases and a 31% increase in CFR.

Lassa fever in Taraba State, 2020-2025





  • As of week 8, 2025, Taraba State reported 411 confirmed cases including 129 deaths (CFR 31%).
  • In 2025 only, Taraba State reported 80 confirmed cases including 25 deaths (CFR 31%).
  • Compared to same period 2024, this represents a 16% increase in the number of confirmed cases and a 27% increase in CFR.

Lassa fever in Ebonyi State, 2020-2025





  • As of week 8, 2025, Ebonyi State reported 270 confirmed cases including 119 deaths (CFR 44%).
  • In 2025 only, Ebonyi State reported 15 confirmed cases including 7 deaths (CFR 47%).
  • Compared to same period 2024, this represents a 50% decrease in the number of confirmed cases and a 12% decrease in CFR.

Lassa fever in Kogi State, 2020-2025





  • As of week 8, 2025, Kogi State reported 154 confirmed cases including 26 deaths (CFR 17%).
  • In 2025 only, Kogi State reported 14 confirmed cases including 4 deaths (CFR 29%).
  • Compared to same period 2024, this represents a 26% decrease in the number of confirmed cases and a 443% increase in CFR.

Lassa fever in Gombe State, 2020-2025





  • As of week 8, 2025, Gombe State reported 59 confirmed cases including 21 deaths (CFR 36%).
  • In 2025 only, Gombe State reported 11 confirmed cases including 6 deaths (CFR 55%).
  • Compared to same period 2024, this represents a 267% increase in the number of confirmed cases and a 64% increase in CFR.

Lassa fever in Benue State, 2020-2025





  • As of week 8, 2025, Benue State reported 166 confirmed cases including 34 deaths (CFR 20%).
  • In 2025 only, Benue State reported 5 confirmed cases including 3 deaths (CFR 60%).
  • Compared to same period 2024, this represents a 88% decrease in the number of confirmed cases and a 260% increase in CFR.

Thank you

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